1. Field of the Invention
The present invention is directed towards a surgical template for use in gynecological procedures, as well as surgical methods employing this template. More particularly, the present invention provides apparatus and methods for ensuring proper placement of a fixation device during gynecological procedures, such as procedures for the correction of female stress urinary incontinence. An urethral sling which may be used in conjunction with the template is also provided.
2. Description of Related Art
Female stress urinary incontinence (SUI), defined as the unintentional loss of urine, can be a socially unacceptable problem for many women. Most often, the incontinence occurs during coughing, sneezing, or physical activity in women afflicted with this problem. While effective surgical treatment for this condition has existed for nearly 50 years, the procedures typically involve major abdominal surgery with accompanying post-operative limitations lasting six to eight weeks. Because of the nature of these surgical procedures, many women simply resort to diaper-like incontinence pads, or simply avoid any activities which result in the unintentional loss of urine.
In the normal resting state, the external pressure exerted on the collapsible urethra by the surrounding musculature is greater than the pressure exerted on the bladder, and therefore continence is maintained. During moments of coughing, sneezing, or physical activities, greater pressure will be exerted on the dome of a filled bladder. In women not afflicted with stress incontinence, a corresponding increase in the external pressure on the urethra acts to prevent the unwanted loss of urine from the bladder. Sufferers of SUI, however, aren't so fortunate.
Stress urinary incontinence is generally caused by two anatomic etiologies: intrinsic sphincter deficiency ("ISD"); and a loss of support of the periurethral tissue at the urethra-vesicular junction ("UVJ"--the region where the urethra enters the bladder). The latter situation (also known as hypermobile bladder neck) often occurs after childbirth, and is caused by a separation of the connective tissue which secures the periurethral tissue to the underside of the pubic bone. When this occurs, the UVJ will sag into the vagina, thereby reducing the pressure which can be exerted on the urethra during moments of stress. Diagnosis of any sagging of the UVJ can be easily determined by inserting the tip of a cotton swab into the urethra until it reaches the UVJ. The patient is then asked to bear down as if urinating, and loss of the UVJ support is readily identified by the upward movement of the wooden end of the cotton swab. In this test, the external urethral meatus acts as a fulcrum for the tip of the swab, and the elevation of the opposite end indicates the downward descent of the UVJ. U.S. Pat. No. 4,072,144 provides an alternative device which may be utilized to readily measure the angle of the UVJ in a similar manner.
ISD, on the other hand, is a functional problem in that the detrusor muscle (also known as the urethral sphincter) does not respond to sudden increases in intra-abdominal pressure. ISD can be caused by muscular withering with age, arteriosclerosis, diabetes, or prior incontinence surgery, all of which are related to a compromised blood supply to the detrusor muscle surrounding the urethra.
It is estimated that 10% of all incontinence is attributable to ISD, and the incidence of ISD is likely to increase as the population ages. For both types of stress urinary incontinence, however, various types of surgical procedures have been developed which often provide relief.
Various "urethropexy" procedures (often referred to as retropubic bladder neck suspension) fix or secure a portion of the tissue adjacent the patient's urethra (also referred to as the periurethral tissue) relative to a structure within the patient's body by means of a fixation device. The first urethropexy procedure for eliminating SUI caused by a sagging urethra was developed in 1948 by Drs. Marshall, Marchetti, and Krantz, and generally involves the fixation of the periurethral tissue at the UVJ on either side of the urethra (MMK procedure). Fixation in the MMK procedure, also known as abdominal culposuspension, is accomplished by suturing the periurethral fascia at the UVJ on either side of the urethra to the periosteum of the pubic bone. The procedure essentially alters the angular relationship between the urethra and bladder by elevating the UVJ, and therefore preventing the sagging of the UVJ when downward pressure is applied to the region by various stresses. The MMK procedure has been perfected by others over the years, however the essential principles have remained the same. Unfortunately, prior to Applicant's work, MMK procedures could only be performed via a large abdominal incision (referred to as an "open" procedure).
In 1955 Burch developed the urethropexy procedure of affixing the periurethral fascia bilaterally to Cooper's ligament, rather than the periosteum of the pubic bone, thereby resulting in a technically easier procedure because of the previous difficulties in passing a needle through the periosteum of the pubic bone. Although the Burch procedure has been performed laparoscopically, the five-year failure rate for the open Burch procedure is approximately 80%. A laparoscopic Burch procedure can be even more problematic since it is extremely difficult and time-consuming to tie sutures laparoscopically. Both the MMK and Burch procedures are referred to as retropubic suspensions.
Alternatively, needle suspension procedures such as those of Pereyra (West. J. Surg., 67: 223, 1959), Stamey (Surg., Gynec. & Obst., 136: 547, 1973), Raz (Urology, 17: 82, 1981), Gittes (J Urol., 138: 568, 1987) and Benderev (J. UroL, 152: 2316, 1994) have been developed for the correction of hypermobile bladder neck. In most of these procedures, a long needle having a suture attached thereto is passed into the abdominal cavity, through the space of Retzius, and through a portion of the periurethral tissue. Several bites of periurethral tissue are usually taken, and anterior fixation of the suture is accomplished by either securing the suture to the rectus fascia or by securing the suture to a bone anchor in the anterior pubis (as in the Benderev procedure). The needle and accompanying suture may or may not enter the vagina, depending upon the procedure and type of needle employed. Multiple passes of the needle through the periurethral tissue are usually employed, and the suture is usually weaved through the periurethral tissue in a helical pattern (or any of a variety of other patterns).
Although needle suspension procedures are often much quicker and simpler than the retropubic MMK and Burch procedures, the long-term failure rate is significantly higher. The gynecological procedures of MMK, Burch and others have proven to be the most effective. This is reputedly due to the lack of retropubic dissection in the needle suspension procedures and the subsequently absent post-operative fixative scarring in the space of Retzius. Scarring of the urethra and periurethral fascia to the undercarriage of the pubic bone also aid in fixation of all of the involved tissues during the MMK and Burch procedures, thereby assisting in the prevention of incontinence. Although these problems could perhaps be rectified by dissection of the space or Retzius during needle suspension procedures in order to promote the growth of fixative scar tissue in this region, such dissection is not always practical when one is attempting to minimize the invasiveness of the procedure by performing a needle suspension.
Failure also occurs because of suture pull-out, which is often caused by the surgeon's failure to take a sufficient bite of periurethral tissue when passing the needle therethrough. Needle suspensions are usually blind procedures which require the passing of long needles through the rectus fascia to the periurethral fascia utilizing a cystoscope or by using the underside of the pubic bone as a guide for the needle. A finger pressed against the vaginal wall may also be used to guide the passing of the needle into the vagina. Although these urological procedures avoid the 10-centimeter midline or Pfannenstiel incision and its' required three-day or longer hospital stay in the open procedures, it is often difficult for the surgeon to locate the proper location in the periurethral tissue through which the sutures should be passed. More significantly, the long needle may inadvertently pass into the bladder or the ureters despite transurethral endoscopic vision. Thus, the inappropriate or nonspecific placement of periurethral sutures contributes to the long-term failure rate of needle suspensions, and can also be directly responsible for interoperative and post-operative complications.
Recently, a modified version of the MMK procedure has been developed which utilizes bone anchors secured directly to the pubic bone on either side of the symphysis for fixation of the UVJ. The apparatus for performing this modified MMK procedure are sold by Mitek Surgical Products, Inc. of Norwood, Mass., and a number of U.S. patents concern these products (see, e.g., U.S. Pat. Nos. 5,207,679, 5,217,486 and 4,899,743). In the Mitek-MMK procedure, a Pfannenstiel incision must be made in the abdomen in order to provide access to the space of Retzius. The space of Retzius is in actuality a "potential" space in that it contains various connective tissues and fats which must be dissected in order to provide sufficient access to this region. In fact, this connective tissue, particularly the areolar adventitial tissue, generally breaks down after vaginal delivery of a child, and this breaking down of the connective tissue often contributes to the onset of SUI in many women.
Once the space of Retzius has been dissected in the Mitek-MMK procedure, small anchors are secured in the pubic bone on either side of the pubic symphysis. Each of the bone anchors has a suture attached thereto, and these sutures are threaded through the periurethral tissue on either side of the urethra. The sutures are then tied off in the abdomen so that the periurethral tissue is pulled upward, which in turn restores the angle of the urethra at the UVJ, thereby restoring the urethra to its proper location. While the Mitek-MMK procedure is highly effective, it is a lengthy and complicated procedure which can generally only be performed by highly-skilled surgeons.
More recent advances in needle suspension procedures include those developed by Theodore Benderev and marketed by Vesica Medical, Inc. of San Clemente, Calif. This procedure is discussed in U.S. Pat. Nos. 5,544,664 and 5,582,188, all of which are incorporated herein by reference. The Benderev procedure differs from most other needle suspensions in that, like the Mitek-MMK procedure, a bone anchor may be used to attach the fixation device (in this case a suture) to the pubic bone. Unlike the Mitek-MMK, however, the bone anchors are secured to the anterior pubis (the topside of the pubic bone), thereby providing a minimally-invasive procedure. In the Benderev procedure, however, the suture extending from the anchor is once again passed blindly from the abdominal cavity into the vagina, thereby complicating proper suture placement.
In all of the above procedures, the fixation device (i.e., the suture) remains permanently within the patient. Scar tissue, however, will form about the fixation device, thereby reattaching a portion of the periurethral tissue directly to the supporting structure (e.g., the pubic bone). When the incontinence is caused by ISD or when the support tissues in the bladder neck area are irreparably damaged, however, the above-described procedures are not the recommended treatment. In these circumstances, a urethral sling procedure (also known as a pubovaginal or suburethral sling procedure) may be employed. In the "sling procedure", a urethral sling comprising a strip of flexible material acts as the fixation device. One end of the sling is typically sutured to the anterior rectus fascia, and the other end is then slung beneath the urethra and likewise sutured to the anterior rectus fascia. In this manner, incontinence is corrected due to the elevation of the UVJ and the compression of the urethra against the symphysis pubis. Similarly to the bladder neck suspension procedures, proper placement of the sling through the periurethral tissue is critical to the success of this procedure, and therefore the incisions in the periurethral tissue through which the sling passes must be precisely located.
The present invention provides a surgical template which may be employed to direct proper placement of a fixation device during a gynecological procedure. The template of the present invention may be employed, with slight modifications to its configuration, in any gynecological procedure wherein a fixation device is connected to a portion of the tissue adjacent the vagina (preferably the periurethral tissue), including bladder neck suspensions (both retropubic and needle suspensions), as well as vaginal sling procedures. In addition, the template of the present invention may be employed in both traditional open procedures as well as recently-developed laparoscopic procedures. By way of example, the template of the present invention may be employed in the MMK, Burch, needle suspension (including Benderev) and sling procedures described above.